Heres the info
I had a head gasket leak. So I had the heads shaved, new bolts, head gaskets, intake manifold gasket, new plenum gasket, new lifters and push rods.

Put it all back together and have a loud hooting noise from the AIC. If you unplug it it stops. Of course the car won't idle unplugged.

Put on a new IAC, Mass air sensor. Still there.

Took it the the Ford garage, they say all sensors are working within normal ranges. They have had it two weeks and can't find the problem. They put a new IAC gasket on, and new throttle body gasket. Still got the loud noise. It does go away abov 3000 rpms.

Could be the gasket or when you put the intake back on you could of cracked it.
Quick test is start the car and spray starting fluid around the sides of the intake where it meets the head and if it revs up you either have a bad gasket or intake. If that dont work let me know.